So, I do believe that majority of guys riding size 54 (considering them smaller, less powerfull) feels R5 as super stiff bike.

Weight nor height of the rider does not have a correlation to their power output. Sorry.There are short guys who ride 48s and barely crack 130lbs who can put out more power than a rider who uses a 56 and stands over 200lbs. Yes the world does have a general bias to people who are taller (business, relationships, etc:.) which often acts blind to the person's actual capabilities, but that bias does not necessarily carry any veracity. To paraphrase what a person might actually learn about human behaviour if you study it enough: "People are idiots."

I will not call you an idiot, even though you said that people could, but assuming a correlation between the size of a rider and their power output is a bit shortsighted, if not naïve.

Ok, let's talk about assumptions.You start off with a blanket statement without any specifics, I countered with "no correlation." Then you throw in a specific scenario? That isn't a blanket statement, that's specific.

Power over what distance?

You are assuming they finish at the same time. You are assuming they are of the same capability. You are assuming a lot which you take for granted (such as the variability of humanity).You are assuming a correlation of height (~frame size) to weight and capability.

You know what they say about assumptions?

Here, let me break your scenario:Rider 1: Short guy... say Purito... plenty of power, yet small. Rider 2: Tall guy. Guess what? Just because he's tall does not mean he puts out the same power. Heck, he might not be as strong of a rider nor experienced?

So with your original statement, just because Purito rides a smaller frame he will always have less power than any rider on a bigger frame? Bullocks.

There. No assumptions of anything specific: they could be any rider. Therefore countering your argument of "frame size correlates to power" general statement.

I am sure, You agree. (all frame producers knows it and use this knowledge in engineering)..... even Cervelo when they were engineering RCA size 58 What a pitty, they did not use the knowledge in the range of 48-56

Last edited by Permon on Fri Jul 05, 2013 12:32 pm, edited 1 time in total.

You're still ignoring a defense of your original statement - that the frame size of the rider correlates to THEIR power output.

So if you see two identical builds up against a cafe wall, one of them size 48 and the other a 56, without seeing who is riding which bike, you are assuming that the person with the smaller frame puts out less power than the taller riders? Again, naïve and shortsighted. Let's go for a ride sometime, I'll wait for you at the top.

And please, is it really necessary to quote the post immediately above yours? A bit inefficient.

In GENERAL, YES. That is a matter of fact. Otherwise You would assume that taller/heavier riders are slower than the small one!

prendrefeu wrote:

So if you see two identical builds up against a cafe wall, one of them size 48 and the other a 56, without seeing who is riding which bike, you are assuming that the person with the smaller frame puts out less power than the taller riders? Again, naïve and shortsighted.

YES, that is exactly what each frame manufacturer has to consider.

prendrefeu wrote:

Let's go for a ride sometime, I'll wait for you at the top.

Funny, You never met me, and You are so sure, You drop me Even if You droped me, I could have used SO MUCH more power to get up the hill than You! Just becasue, I could be heavier than You (to get more weight up the hill = more power to do it in a certain time.....) Even if You get up there 5minutes earlier and I ll be 150kg, YES, I would be the one who put MUCH MORE POWER to the bike (absolute numbers, not watt/kg)

We live in a World which measures cycling performance in TIME, the sooner You are at the finish line, the better You are. Right? So, who uses more power to get to the finish line wheel to wheel considering Purito and Greipel???Yes, Greipel.

And one more thing.....if You are taller... the frameset tubes are longer, Your arms and legs are longer. You need MORE material to deal with it. Simple as it is.

Lets stop this discussion....this thread is about RCA.

Last edited by Permon on Fri Jul 05, 2013 12:19 pm, edited 2 times in total.

Good observation - the rider's characteristics have a lot to do with how a bicycle feels.

Regarding the uneven steps in weight from one size to the next, a lot of the change in weight has little to do with stiffness, and more to do with strength. As top and down tube get farther apart, they are better positioned to brace against loads coming in through the head tube. This affects the frames' frontal strength differently for different frame sizes. There are other examples as well (seat tube cluster, etc.).

But this natural phenomenon also corrupted by the legal requirement to meet the "same" strength standard, regardless of size. Which explains why the smaller sizes don't get lighter as quickly - they have less leverage but must be just as strong.

These effects show up mostly with highly engineered frames, where we approach the limits. It doesn't happen as much with metal frames. Cut off some tube, lose some weight.

P.S. by accident I was reading those 3 articles in the section "Ask The Engineers" on cervelo.com this Tuesday Looking forward for the upcomming articles. Very usefull to get some "insider" information. GREAT JOB You do!

You're still ignoring a defense of your original statement - that the frame size of the rider correlates to THEIR power output.

So if you see two identical builds up against a cafe wall, one of them size 48 and the other a 56, without seeing who is riding which bike, you are assuming that the person with the smaller frame puts out less power than the taller riders? Again, naïve and shortsighted. Let's go for a ride sometime, I'll wait for you at the top.

And please, is it really necessary to quote the post immediately above yours? A bit inefficient.

Something for You, Specialized has news for 2014:

"All the Tarmac and Roubaix bikes get SL4 size-specific engineering, which recently only applied to the top models.The technology means that each frame size gets its own shapes, layups, seatstays, chainstays, forks and bearings. The thinking is that a smaller rider has different needs to a taller rider; a 49cm bike shouldn’t be as stiff as a 61cm one."

But I guess You are smarter than producers and will keep on telling me, that 48 size frame has to carry the same load as size 61 Maybe Specialized should hire You....their egineering team made a real big mistake in engineering 2014 model range You go and tell them!

Permon. I won't call you daft, but I will ask if you have a reading comprehension difficulty.

Please, go back and read the arguments between us. WHERE did I state that the frames should be designed equally between sizes?You have a complete misunderstanding here of the difference between the power output of a rider and the forces a rider's body puts upon a frame. Do you know the difference? Apparently not because you are still trying to claim the same argument against me.

And, again, there is no direct correlation between the size of the rider (as judged by their chosen frame size) and their power output if you are judging purely on the size of the frame without looking at the rider. Your statement is as naïve as someone stating that they can judge a person's intelligence by whether they are wearing corrective lenses or not because they need to strain their eyes to see.

Basic physics tells us that larger objects exert different forces upon an object compared to smaller ones (in this case, a frame). No shit, Sherlock. That's basic secondary school physics. NO ONE is disagreeing with you there. That's not what I'm questioning. If there are different forces on a frame the frame needs different designs and layups. Yep. That does not mean that the taller rider will necessarily, outright, without-question-all-the-time put out more power than the smaller rider. Do you know the difference?

Now, I've stated here in this very post and in every single post leading up to this what - exactly - am I questioning from your original statement. Please go back and read it. I'll wait. In the meantime, pulling up references which refer to FORCES and not POWER output is just making you seem like you have reading comprehension difficulties.

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